1. Field of the Inventions
The present inventions relate to control devices for engines of boats, and more particularly, to control devices that provide enhanced vessel speed control.
2. Description of the Related Art
Modern boats are typically provided with a power request device disposed in the operator's area, which is also known as a cockpit. The power request device can be constructed in various ways (e.g., a pedal), but is typically in the form of a lever. Often, such a lever is connected to the engine of the boat with a plurality of cables for controlling both the power output of the engine, and where the boat has neutral and/or reverse gears, the gear position.
Recently, marine propulsion system manufacturers have adapted digital communication network systems for connecting various components of such propulsion systems. In these networks, user controls and gauges, such as throttle levers and tachometers, can be connected to the associated engine through a digital network. These networks simplify the electrical wiring needed for such a boat and also provide great flexibility.
In these systems, a throttle lever, for example, will include a sensor which converts a physical position of the lever into an electronic signal. The electronic signal can than be transmitted to the engine directly, or over a digital communication network. Additionally, although a particular gauge or input device is connected to the engine with a hard wire, or through a digital communication network, the gauge or input device can also be mechanically connected to the engine to provide control if the network is not used or is inoperable.
Where a boat uses an electronically enabled control, such as a throttle or “control” lever, an electric signal corresponding to a position, or an angle, of a control lever (displacement) is transmitted to a control section in the engine controller of the engine. The control section controls a throttle actuating unit for actuating a throttle valve of the engine incorporated in an outboard motor, for example, to control the engine speed. The desired position of the throttle valve is determined based on the displacement of the control lever with reference to a “map” in which the relation between the displacement of the control lever and the desired throttle valve opening is stored. A throttle actuating unit is operated so that the throttle valve is moved to the desired position.
In at least one known system, when the throttle valve does not reach the set position within a predetermined period of time, the relation between the displacement and the actuating amount stored in the map is corrected (see e.g. Japanese Patent Publication Hei 8-296473 (pp. 1 to 2 and FIG. 3)).